I have a couple of big files that I would like to compress. I can do this with for example

tar cvfj big-files.tar.bz2 folder-with-big-files

The problem is that I can't see any progress, so I don't have a clue how long it will take or anything like that. Using v I can at least see when each file is completed, but when the files are few and large this isn't the most helpful.

Is there a way I can get tar to show more detailed progress? Like a percentage done or a progress bar or estimated time left or something. Either for each single file or all of them or both.

You can use pv to achieve this. To report the progress correctly, pvneeds to know how much bytes you are throwing at it. So, the first step is to calculate the size (in kbyte). You can also completely drop the progress bar and just let pv tell you how much bytes it has seen; it would report a 'done that much and that fast'.

Cool. pv doesn't seem to come with Mac OS X, but will try this out once I have a computer with MacPorts on it. Could you explain what you are doing there though? Not quite sure what the first line does exactly.
– SvishJul 28 '10 at 12:10

4

first line: fetch info about how many bytes will be handled. second line: use the size from the first line to allow pv to render 'progress'. since you are piping data, pv does not know how many more bytes will come.
– akiraJul 22 '11 at 10:25

One addition: SIZE=$(($SIZE * 1000 / 1024)) - I don't know whether or not this is a quirk on my particular platform, so I'm not adding it to the answer: du returns size where 1 kb = 1024 bytes, while pv seems to be expecting 1 kb = 1000 bytes. (I'm on Ubuntu 10.04)
– IzkataDec 11 '11 at 2:27

2

@lzkata you could always ask du to use your preferred blocksize, e.g. du -s --block-size=1000, or just work with plain bytes, e.g. drop the k's from the du and pv calls. Nevertheless, I would expect both to use 1024 unless told otherwise, e.g. the --si switch on du, for example.
– LegolasFeb 23 '12 at 11:05

1

or just drop the k-stuff and just use plain bytes (du -sb and pv -s without any modifier). that should end all the confusion.
– akiraFeb 23 '12 at 11:10

This is works for extraction, but you still need to do one of the more complicated commands for creation (which was the original question). It could still be combined with those; it's just more complicated.
– Daniel HAug 9 '14 at 5:05

Just noticed the comment about MacOS, and while I think the solution from @akira (and pv) is much neater I thought I'd chase a hunch and a quick playaround in my MacOS box with tar and sending it a SIGINFO signal. Funnily enough, it worked :) if you're on a BSD-like system, this should work, but on a Linux box, you might need to send a SIGUSR1, and/or tar might not work the same way.

The down side is that it will only provide you with an output (on stdout) showing you how far through the current file it is since I'm guessing it has no idea about how big the data stream it's getting is.

So yes, an alternative approach would be to fire up tar and periodically send it SIGINFOs anytime you want to know how far it's gotten. How to do this?

The ad-hoc, manual approach

If you want to be able to check status on an ad-hoc basis, you can hit control-T (as Brian Swift mentioned) in the relevant window which will send the SIGINFO signal across. One issue with that is it will send it to your entire chain I believe, so if you are doing:

This works nicely if you just want to check if that tar you're running is stuck, or just slow. You probably don't need to worry too much about formatting issues in this case, since it's only a quick check..

The sort of automated approach

If you know it's going to take a while, but want something like a progress indicator, an alternative would be to fire off your tar process and in another terminal work out it's PID and then throw it into a script that just repeatedly sends a signal over. For example, if you have the following scriptlet (and invoke it as say script.sh PID-to-signal interval-to-signal-at):